Metal enclosed switchgear



Jan. 21, 1947. P, R P|ER5QN TAL 2,414,555

y METAL ENCLOSED -SWITCHGEAR Filed Feb. 2, 1943 2 Sheets-Sheet lPatented 21, 1947 METAL ENCLOSED SWITCHGEAR Paul R. Pierson,Wilkinsburg, and Gilbert C. Sinclair, Murrysville, Pa., assignors toWestinghouse Electric Corporation, East Pittsburgh, Pa., a corporationof Pennsylvania Application February z, 194s, serial No. 414,484

Our invention relates, generally. to switchgear and, more particularly,to metal-clad switchgear of the type in which switchgear apparatus, suchas oil circuit breakers, is enclosed in metal cells or compartments.

In such switchgear, the circuit breakers are usually removable from ,thecompartments for inspection and repair, and it is essential that thebreakers be isolated from all `energized conductors before such removal.In switchgear of the type known as "vertical lift, each circuit breakerunit'may be disconnected from the power conductors'by lowering thebreaker in the cell prior to its removal from the cell. However, theraising and lowering of heavy duty circuit breakers having large tankscontaining oil is rather didicult and requires complicated and expensiveelevating mechanisms.

In order to avoid the use of such elevating mechanisms, isolating ordisconnecting switches 'have been proposed for mounting in the cellin Amore speciilc object of our invention is to provide a simpliiled andimproved means for isolating an venclosed circuit breaker from power.conductors.

Another object of our invention is to provide an isolating switch for anenclosed circuit breaker which shall be removable from the enclosed cellwith the circuit breaker unit.

^ Afurther object of our invention is to provide for interlocking theoperating mechanisms of a circuit breaker and its associated isolatingswitch.

Other objects of our invention `will be explained fully hereinafter orwill be apparent to those skilled in the art.

In accordance with our invention, telescoping contact members are somounted on the breaker terminals that theycan be extended or retractedto complete or disconnect the circuits between the breaker terminals andthe stationary disconnecting contacts in the cell structure. 'I'hetelescoping contact members and their operating mechanism are mounted onthe breaker unit and are removable from the cell with the breaker. Theoperating mechanisms for the breaker and the disconnecting device are sointerlocked that the disconnecting device cannot be extended or 6Claims. (Cl. 20D- 50) 2 cannot be closed with the device in anintermediate position. l

For a fuller understanding of the nature and objects of our invention,reference may be had to the following detailed description taken inlconjunction with the accompanying drawings, in which:

Figure l is a view, partially in front elevation and partially .insection, of a metal-clad switchgear structure embodying our invention;

Fig. 2 is a view, partially in end elevation and partially in section,of the structure shown in Fig. 1; fand,

Fig. 3 is an enlarged view, in section, ofthe disconnecting device forone terminal of a circuit breaker.

Referring to the drawings and, particularly, to Figs. l and 2thestructure shown therein comprises a cell I0 for enclosing a removablecircuit breaker II. As shown, the cell I'Ii is preferably comprised ofsheets supported by angle bars and is divided into an upper compartmentI2, only a portion of which is shown, and a lower compartment I3 whichare separated by a metal partition Il. A, plurality of insulatingsupports I5 for conductors I6 are fixed in the partition Il,

In accordance with the usual practice, the terminal conductors I6 may beconnected to bus bars or other power conductors (not shown) As shown inFig. 3, each one of the insulating supports I5 comprises a cylindricalbushing comvphase type and comprises three individual tanks I8 which aremounted in a framework i9 supported by wheels 2'I. Thus, the circuitbreaker may be rolled into and out of the cell I0 on tracks 22 providedin the foundation or iioor of the cell. A suitable mechanism 23 foroperating the contact members of the circuit breaker, which are disposedin the tanks I8, is mounted on the, framework I9. As shown, eachbreakertank is provided with an operating crank 24, and all of the cranks areconnected together by a connecting link 25 to be simultaneously operatedby the mechanism 23 through a suitable linkage 26. 'I'he mechanism 23may be of any standard type well known in the art and, therefore, willnot be described in more detail in the present speciflcation.

In accordance with the usual practice, the mechanism 23 is provided witha tripping device for opening the contact members of the circuitbreaker. A manuallyy operated lever 21 is provided for actuating thetripping mechanism. It

retracted with the breaker closed, and the breaker o0 will be understoodthat the tripping mechanism may also Ybe electrically operated .in amanner well known in the art. The tripping lever 21 is connected to ashaft 28 which is rotatably mounted in a support 28 on the circuitbreaker frame I9. 'I'he function of the shaft 28 will be explained morefully hereinafter. v

As shown, each phase of the circuit breaker unit is provided with a pairof terminals 3| which are externally mounted on the tanks I8 of thelcircuit breaker. The terminals 3| are each provided with an uninsulatedportion 32 which extends above the insulated portion of the terminal.

In order that the circuit breaker terminals may be connected to anddisconnected from the corresponding conductor terminals I6 withoutchanging the position of the circuit breaker unit in the cell, we haveprovided an isolating or disconnecting ydevice 38 which may be operatedto connect the breaker terminals and the conductor terminals withoutelevating the complete breaker unit in the cell. The disconnectingdevice 33 comprises a plurality of telescoping or extensible terminalswhich may be extended or collapsed to complete or disconnect thecircuits between the breaker terminals and the stationary conductorterminals in the cell.

As shown in Fig. 3, each disconnecting terminal comprises a cylindricaltube 33 which is preferably comprised of copper or other suitableconducting material and is mounted in an insulating sleeve 35 whichtelescopes'over the circuit breaker bushing 3l. The sleeve 33 is securedin the upper end of the insulating sleeve 35 by means of a metal collar36.

Primary disconnecting contacts 31 of the type ordinarily used inmetal-clad switchgear are provided at each end of the metal sleeve` 3d.Thus, when the sleeve 35 is in its elevated or extended position, asshown in Fig. 3, it bridges the stationary terminal I6 and the breakerterminal 32, thereby completing an `electrical circuit between these twoterminals. When the metal sleeve 3B and its supporting insulating sleeve35 are in their lowered or retracted position, as indicated by thebroken lines, the circuit between the terminals I6 and 32 isinterrupted.

The porcelain sleeves 3.5 are all mounted in an.

elevating framework 38. A flanged ring 39 surrounds each porcelainsleeve 35 for securing it in the elevating framework 38. Guide members4I are provided on the circuit breaker frame I3 for directing themovement of the elevating frame 38.

An elevating or actuating mechanism is provided for raising and loweringthe frame 38 and the bridging contact members of the disconnectingdevice. The elevating mechanism comprises a 'pairof jack screws 2 whichmay be raised and lowered by jacks 83. In this instance, one of thejacks is driven by a shaft M and the other is driven through a chain 85connected to the shaft 34. The shaft 34 may be rotated by a removablecrank (not shown), which may be placed on the end of the shaft. Theentire elevating mechanism may be mounted on the circuit breaker frameby vertical supports 46 and horizontal supports 41.

Thus, the entire elevating or actuating mecha- 'nism and disconnectingcontact members may be removed from the cell with the circuit breakerunit when the disconnecting /device is in its lowered position. In thismanner, the disconnecting device and its operating mechanism, as well asthe circuit breaker unit, may beremoved from the cell for inspection andrepair.

compartment I3 for lclosing the openings in the insulating bushings I5to prevent access to the terminals I6 when the circuit breaker unit isremoved from the cell. As shown, the shutter 38 is of the slidable typeand is actuated by a cam 38 carried by the frame 38 of the disconnectingdevice. Thus, when the disconnecting device is lowered or retracted, theshutter 38 is closed to prevent access to the energized conductorterminals.

In order to prevent improper operation of the disconnecting device, aninterlocking mechanism 5I is provided for preventing either the openingor the closing of the circuit between the breaker terminals 32 and theconductor terminals I8, while the circuit breaker contacts are closed.The present interlocking device also prevents closing of the contactmembers of the circuit breaker, while the disconnecting device is in anintermediate position. However, the circuit breaker can be operated inthe usual manner to close its contact members for testing purposes whenthe disconnecting device is in its fully lowered or retracted position.

The interlocking device comprises a bar 52 which is pivotally mounted ona side of the cell I8 by means of a support 53. A downwardly extendingmember 58 and an upwardly extending member 55 are provided on theelevating frame 38 for engaging horizontally extending projections 58and 51, respectively, on the opposite ends of the bar 52. A verticallydisposed shaft 58 is slidably mounted in guide members 59 and 6I on theside of the cell I0.

The shaft 58 is biased upwardly by a spring 62, the upper end of whichengages a collar 63 on the shaft 58 and the lower end of which rests on'the guide member BI. A collar 83 on the shaft 58 engages the guidemember 6I to limit the upward movement of the shaft. The lower end ofthe shaft 58 engages an arm 65 which is secured to the end of the shaft28 opposite the tripping arm 21. The upper end of the shaft 58 isprovided with a pair of spaced pins 66 and 61 one of which is disposedabove and the other below the bar 52, thereby loosely connecting the bar52 and the shaft 58.

Referring to Fig. 2, it will be seen that when the frame 38 of thedisconnecting device is lowered, or retracted the member 54 engages theprojection 58 of the bar 52, thereby actuating the bar to the positionindicated by the broken lines and forcing the shaft 58 downwardly tocompress the spring 62. The downward movement of the shaft 58 actuatesthe arm 65 to operate the tripping mechanism of the circuit breaker,thereby opening the contact members of the circuit breaker before thebridging members of the disconnecting device arewlowered to a positionto interrupt the circuit established by the bridging members through thebreaker terminals and the conductor terminals.

When the disconnecting device is in its completely lowered or retractedposition, the downwardly extending-member 54 clears the projection 56 ofthe bar 52, and the spring 82 raises the bar to its horizontal position,as shown by the full lines in Fig. 2. Thus, the tripping mechanism ofthe breaker is relea-sed and the breaker may be closed, if desired.

However, it is impossible to raise the disconnecting device to establisha circuit between the breaker terminals and the conductor terminals bymeans of the disconnecting device. while the position. In this mannerthe tripping mechanism is released after the disconnecting device is inits fully closed position and the contact members of the breaker may beclosed in the usual manner. It will be seen that the breaker cannot beclosed while the disconnecting device is in an intermediate position,since the tripping mechanism is not released by the clearance of the bar52 until the elevating frame 38 is in substantially its fully lowered orfully raised position, thereby clearing the bar 52 from the members 54or 55.

When the elevating frame 38 of the disconnecting device is in itsfullylowered or retracted position, the breaker unit and the completedis.- connecting device may be removed from the cell in the usual mannerwithout interference by the interlocking mechanism. Thus, thedisconnecting device and its operating mechanism may be made availablefor inspection as well as the circuit breaker mechanism. The presentstructure affords all the usual advantages of metal-enclosed switchgearwithout requiring the provision of elevating mechanism suitable forraising and lowering the complete circuit breaker unit. As explainedhereinbefore, circuit breakers suitable for use in high voltage and highcurrent capacity systems are necessarily heavy in weight and requirecomplicated and expensive elevating mechanisms. Therefore, the presentdisconnecting device is particularly suitable for use with heavy dutycircuit breakers, although it may be utilized with circuit breakers ofany type.

tuating the bridging members vertically relative to the lcircuit breakerto connect said circuit breaker terminals and said conductor terminals,said bridging members and said actuating means being removable from thecell with the circuit breaker unit.

3. Switchgear apparatus comprising, an enclosing cell,. a circuitbreaker unit horizontally removable from the cell, a round lterminalexternally mounted on the circuit breaker in fixed relation thereto, around terminal fixed in the cell in predetermined relation to theterminal on the breaker, a cylindrical sleeve slidablyv disposed on thebreaker terminal externally of the breaker, and means disposedexternally of the circuit breaker for actuating said sleeve to engageand disengage theterminal in the cell, said actuating means beingcarried by the breaker unit and removable therewith from the cell.

4. Switchgear apparatus comprising an enclosing cell, a circuitbreakerunit removably disposed in the cell, said circuit breaker havingterminals externally mounted thereon in fixed relation thereto,conductor terminals fixed in the cell, bridging members carried by thecircuit breaker unit and disposed externally thereof, means disposedexternally of the circuit breaker for moving the bridging membersrelative to the circuit breaker to connect and disconnect said circuitbreaker terminals and said conductor terminals, means for tripping thecircuit breaker mechanism, and interlocking means mounted on the cellstructure and actuated by said means for moving the bridging members tooperate said tripping means, said bridging members and the means formoving them relative to the -circuit breaker being removable from thecell with the circuit breaker unit without interference by said Ainterlocking means.

Since numerous changes may be made in the l above described constructionand dierent embodiments of the invention may be made without departingfrom the spirit and scope thereof, it is intended that all mattercontained in the foregoing description or shown in the accompanyingdrawings shall be interpreted as illustrative and not in a limitingsense.

We claim as our invention:

l. Switchgear apparatus comprising, an enclosing cell, a circuit breakerunit removably disposed in the cell, said circuit breaker havingterminals externally mounted thereon in xed relation thereto, conductorterminals xedin the cell, bridging members carried by the circuitbreaker unit and disposed externally thereof, and means disposedexternally of the circuit breaker forl actuating the bridging membersrelative to the circuit breaker to connect said circuit breakerterminals and said conductor terminals, said bridging members and saidactuating means 'being removable from the cell with the circuit breakerunit.

2. Switchgear apparatus comprising, an enclosing cell, a circuit breakerunit horizontally removable from the cell, terminals externally mountedon the circuit breaker in fixed relation thereto, conductor terminalsxed in the cell, bridging members carried by the circuit breaker unitand disposed externally thereof, and means disposed externally of thecircuit breaker for ac- 5. In switch'gear apparatus, the combinationwith an enclosing cell having conductor terminals fixed therein and acircuit breaker unit removably disposed in the cell and having terminalsexternally mounted thereon in iixed relation thereto, of an isolatingswitch disposed externally of the circuit breaker for connecting anddisconnecting the conductor terminals and the breaker terminals, saidisolating switch being carried by the breaker unit and removabletherewith from the cell, means carried by the breaker' unit and disposedexternally of the circuit breaker for operating the isolating switch, atripping mechanism for the circuit breaker, and interlocking meansactuated by operation of the isolating switch for operating saidtripping mechanism.

6. In switchgear apparatus, the combination with an enclosing cellhaving conductor terminals fixed therein and a circuit breaker unitremovably disposed in the cell and having terminals externally mountedthereon in fixed relation thereto,

of an isolating switch disposed externally of the circuit breaker forconnecting and disconnecting the conductor terminals and the breakerterminals, said isolating switch |being carried by the

